Thanisorn SukakulCecilia SvedmanJakob DahlinOla BergendorffLena HolmströmMagnus BruzeSiriraj HospitalLunds Universitet2022-08-042022-08-042021-11-01European Journal of Dermatology. Vol.31, No.6 (2021), 741-74319524013116711222-s2.0-85124175159https://repository.li.mahidol.ac.th/handle/20.500.14594/77673Background: A patient received enoxaparin sodium subcutaneous injections for prophylaxis after surgery and developed inflammatory skin reactions on injection sites on Day 5 after the first administration. Patch test was performed with baseline series and low-molecular-weight heparins (LMWHs) at different concentrations and showed positive reactions to neomycin and LMWHs. Cross-reactivity between neomycin and LMWHs was suspected due to similar structure. Objectives: To establish the evidence of possible cross reaction between neomycin and LMWHs by patch testing. Materials & Methods: Patch testing of 12 individual controls with a history of neomycin contact allergy was performed. Results: Positive patch test reactions to enoxaparin sodium, tinzaparin sodium, and neomycin sulphate were reported in the patients. None of the controls reacted to LMWHs. Conclusion: There was no proof of cross reaction between neomycin and LMWHs in this study, suggesting that the simultaneous reaction may be a coincidence. Since the number of individuals studied was low, allergy to LMWHs following injection in individuals with a history of neomycin allergy should be further investigated.Mahidol UniversityMedicineArticleSCOPUS10.1684/ejd.2021.4164